The invention is based on a fuel injection device for internal combustion engines as defined hereinafter. German Offenlegungsschrift 37 00 687 discloses a fuel injection device of this kind in which a high pressure fuel pump supplies fuel from a low pressure chamber to a high pressure accumulation chamber, which communicates via high pressure lines with the individual injection valves, which protrude into the combustion chamber of the internal combustion engine to be fed; this common pressure storage system is maintained at a determined pressure by a pressure control device. To control the injection times and injection quantities at the injection valves, one electrically actuated control valve is inserted into each high pressure line of each injection valve; by its opening and closing, it controls the high pressure fuel injection at the injection valve.
An additional pressure storage chamber is provided in the known fuel injection device for each injection valve, which chamber is filled by the common pressure storage system and which is likewise connected to the injection valve next to the high pressure line leading from the high pressure accumulation chamber. By means of this division of the storage volume at each injection valve into two pressure chambers, which communicate with each other by means of a line of a determined length, the course of injection can be optimally adapted to the needs of each internal combustion engine, in connection with a throttled flow of fuel out of a pressure chamber, which acts upon the valve member of the injection valve; in particular, a slow pressure buildup can be achieved at the onset of injection and a higher pressure buildup can be achieved at the end of injection. The fuel quantity supplied to the injection valve directly from the common high pressure accumulation chamber is used merely as a means of controlling the reciprocating motion of the valve member of the injection valve, while the entire injection quantity is taken from whichever pressure storage chamber is smaller.
The known fuel injection device, though, has the disadvantage that because of the hydraulic communication between the pressure storage chamber and the pressure chamber at the injection valve member, the high system pressure constantly impinges on the injection valve member, thus putting a high mechanical load on the injection valve.
Furthermore, the control of the injection process is produced by means of the hydraulic blocking or relieving of a pressure chamber at the valve member of the injection valve by the pressure fluctuations of the fuel in the pressure storage system. The control events at the individual injection valves can mutually affect one another via the high pressure lines which connect them, which leads to imprecisions. Furthermore, the disposition of two high pressure lines per injection valve and the attendant pressure connections increases the cost, so the known fuel injection device does not meet the current strong demand for a structurally simple design, higher injection precision over a long service life, and high operational reliability.